A security system disclosed in, for example, Patent Literature 1 notifies to an outside by activating an alarm upon detection of intrusion of a suspicious individual into a facility, such as a home.
A security system disclosed in Patent Literature 2 identifies whether a visitor is an authenticated delivery person by comparing a face image of the visitor captured by a camera with a pre-registered face image of the delivery person. A technique of identifying whether a visitor is a pre-registered individual by comparing face images is popular as a face recognition technology.